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Construction is almost 80% complete
The sewer tunnel is 22 feet in diameter and will be six miles long. The tunnel route begins at SE 17th and McLoughlin Blvd. and will end on Swan Island where it will be connected to the Confluent Shaft. The tunnel boring machine (TBM) started boring in May 2007 from the Opera Shaft and is moving north towards the Port Center Shaft at the Swan Island Pump Station. From there, the TBM will be removed and transported back to the Opera Shaft to tunnel south towards the McLoughlin Shaft.
The Confluent Shaft connects to the Swan Island Pump Station. The pump station will pump sewage through the Portsmouth Force Main, a pressurized pipe Environmental Services will build as one of the East Side CSO projects. The force main will discharge to an existing tunnel, which will take the flow to the Columbia Boulevard Wastewater Treatment Plant.
Shafts Seven shafts are being built along the alignment. The shafts will connect existing overflow pipes to the East Side CSO Tunnel and provide aboveground access to the tunnel. The shafts are approximately 49 - 60 feet in diameter and 110 to 165 feet deep.
Project Schedule
¤ February 2003 Design Team Selected - Project Began
¤ July 2004 Preliminary Design - Completed
¤ February 2006 Final Design - Completed
¤ March 2006 Shaft Construction Began
¤ May 2007 Tunnel Excavation Began
¤ October 2009 North Drive Completed
December 2011 East Side Big Pipe Completed
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